Electrically conductive, transparent, translucent, and/or reflective materials

ABSTRACT

In one aspect, microporous membranes are described herein demonstrating composite architectures and properties suitable for electronic and/or optical applications. In some embodiments, a composite membrane described herein includes a microporous polymeric matrix or substrate having an interconnected pore structure and an index of refraction and an electrically conductive coating deposited over one or more surfaces of the microporous polymeric matrix. In other embodiments, the pores are filled and the membranes are substantially transparent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of and priority to U.S. patentapplication Ser. No. 14/687,131 filed Apr. 15, 2015, now U.S. patentSer. No. 10/030,157, which claimed the benefit and priority to U.S.Provisional Application No. 61/979,564 filed Apr. 15, 2014, both ofwhich are hereby incorporated herein by reference in its entirety.

FIELD

In accordance with at least selected embodiments, the present inventionrelates to conductive, transparent, translucent, and/or reflectivepolymeric membranes or materials, substrates for such membranes ormaterials, methods of production of such substrates, membranes ormaterials, and/or methods of use of such substrates, membranes ormaterials. In accordance with at least selected embodiments, the presentinvention relates to electrically conductive membranes or materials,preferably electrically conductive transparent membranes or materials,new or improved porous or microporous substrates for such membranes,methods of production of such conductive membranes or materials, and/ormethods of use of such membranes, materials or substrates.

BACKGROUND

Microporous membranes have been extensively studied and developed forvarious separation and/or diffusion applications. Microporous membranes,for example, are widely used in air and water filtration applications aswell as separator films in battery constructions. Various single ormultiple layer Celgard® microporous polymeric membranes are manufacturedand marketed by Celgard, LLC of Charlotte, N.C.

Typically, the insulative properties and organic construction of manymicroporous membranes often renders them unsuitable for electricallyconductive applications and applications involving high temperature,oxidative, and other corrosive environments.

SUMMARY

In accordance with at least selected embodiments, the present inventionmay address the above need for microporous membranes suitable forelectrically conductive applications and/or applications involving hightemperature, oxidative, and/or other corrosive environments, and/orrelates to conductive, transparent, translucent, partially reflective,and/or reflective polymeric membranes or materials, substrates for suchmembranes or materials, methods of production of such substrates,membranes and/or materials, and/or methods of use of such substrates,membranes and/or materials. In accordance with at least selectedembodiments, the present invention relates to electrically conductivemembranes or materials, preferably electrically conductive transparentor semi-transparent membranes or materials, new or improved porous ormicroporous substrates for such membranes, methods of production of suchconductive membranes or materials, and/or methods of use of suchmembranes, materials or substrates.

In one aspect, membranes or microporous membranes are described hereindemonstrating composite architectures and properties suitable forelectronic and/or optical applications. In some embodiments, a compositemembrane described herein includes or comprises a microporous polymericmatrix or substrate having an interconnected pore structure and an indexof refraction and an electrically conductive coating deposited over oneor more surfaces of the microporous polymeric matrix. The compositemembrane can further include or comprise filler material in the porestructure of the polymeric matrix or substrate, the filler materialpreferably having an index of refraction substantially matching theindex of refraction of the polymeric matrix. Further, compositemembranes having constructions described herein can be transparent orsubstantially transparent.

In another aspect, optoelectronic devices are provided incorporatingcomposite membranes described herein. In some embodiments, anoptoelectronic device is a touchscreen device comprising a display and acomposite membrane positioned over the display, the composite membranepreferably including or comprising a microporous polymeric matrix orsubstrate having an interconnected pore structure and an index ofrefraction. An electrically conductive coating is deposited over one ormore surfaces of the microporous polymeric matrix. In being positionedover the display, the composite membrane can be or can be made to betransparent or substantially transparent.

In a further aspect, methods of making composite membranes are describedherein. A method of making a composite membrane, in some embodiments,comprises providing a microporous polymeric matrix or substrate havingan interconnected pore structure and an index of refraction anddepositing an electrically conductive coating or material over one ormore surfaces of the microporous matrix. Further, filler material can bedeposited in the pore structure of the polymeric matrix, the fillermaterial having an index of refraction substantially matching the indexof refraction of the polymeric matrix. Such filler material can be addedbefore, during or after deposition of the conductive or reflectivecoating or material.

These and other aspects, objects or embodiments are described in greaterdetail in the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a surface scanning electron microscopy (SEM) image of amicroporous polymeric matrix or substrate according to one embodimentdescribed herein.

FIG. 2 is a surface SEM image of a microporous polymeric matrixaccording to another embodiment described herein.

FIG. 3 is a surface SEM image of a microporous polymeric matrixaccording to yet another embodiment described herein.

FIG. 4 is a cross-sectional SEM image of a microporous polymeric matrixcomprising a multilayer structure illustrating compositional andmorphological gradients according to one multilayer embodiment describedherein.

FIG. 5 includes photographic images showing side by side comparison of,on the left, the white uncoated (non-metalized) surface or side of amembrane and, on the right, the reverse, metallic, shiny or reflectiveside of the same metalized or coated membrane or material having amicroporous polymeric matrix according to a particular embodiment of thepresent invention.

FIG. 6 is a photographic image of the metalized membrane or material ofFIG. 5 placed over a display screen of a consumer electronic device, inparticular, a BlackBerry device, with the filled portion of themetalized membrane or material (the portion on the left, through whichthe device screen shows) being transparent or translucent and theunfilled portion (the portion on the right, still over the devicescreen) being opaque and reflective without the device screen showingthrough the material in such portion.

FIG. 7 is a surface SEM image of the metalized surface of the metalizedmembrane or material of FIG. 5 at 1,000× magnification.

FIG. 8 is a surface SEM image of the metalized surface of the metalizedmembrane or material of FIG. 5 at 5,000× magnification.

FIG. 9 is a surface SEM image of the metalized surface of the metalizedmembrane or material of FIG. 5 at 20,000× magnification.

FIG. 10 includes (A) a top view and (B) a cross-sectional view of a baremembrane before coating in accordance with embodiments described herein;the membrane is opaque and white (or blue) in appearance because of itsporosity and is electrically insulating.

FIG. 11 includes (A) a top view and (B) a cross-sectional view of themembrane of FIG. 10 after one surface has been coated with anelectrically conductive coating (such coating is red in FIG. 11); themembrane appears opaque and shiny (reflective) because of thecombination of the membrane's porosity and the electrically conductivecoating and is now electrically conductive on the metalized surface.

FIG. 12 includes (A) a top view and (B) a cross-sectional view of themembrane of FIG. 11 after the pores have been filled (such filler isgreen in FIG. 12); the membrane appears transparent and/or translucentbecause the pores are filled and is still electrically conductive due tothe electrically conductive coating (red in FIG. 12).

FIG. 13 includes (A) a top view and (B) a cross-sectional view of themembrane of FIG. 12 after the pores have been over-filled with the samefiller depicted in FIG. 12 (such filler is green in FIG. 13); themembrane appears transparent and/or translucent because of the filler inthe pores. Areas 1 and 2 remain electrically conductive because of theelectrically conductive coating.

DETAILED DESCRIPTION

Embodiments described herein can be understood more readily by referenceto the following detailed description and examples and their previousand following descriptions. Elements, apparatus and methods describedherein, however, are not limited to the specific embodiments presentedin the detailed description and examples. It should be recognized thatthese embodiments are merely illustrative of the principles of thepresent invention. Numerous modifications and adaptations will bereadily apparent to those of skill in the art without departing from thespirit and scope of the invention.

Composite membranes described herein may demonstrate constructionspermitting their use in a variety of applications, including electronicdevice and optical applications. A composite membrane described hereinpreferably comprises a microporous polymeric matrix, substrate or filmhaving an interconnected pore structure and an index of refraction andan electrically conductive coating deposited over one or more surfacesof the microporous polymeric matrix. The composite membrane can furthercomprise filler material in the pore structure of the polymeric matrix,the filler material having an index of refraction substantially matchingthe index of refraction of the polymeric matrix.

Turning now to specific components, a preferred composite membranecomprises a microporous polymeric matrix or substrate having aninterconnected pore structure. The microporous matrix can be fabricatedfrom a variety of polymeric materials. For example, the microporousmatrix can be formed of one or more polyolefins (POs), includingpolyethylene (PE), polypropylene (PP) or copolymers thereof.Alternatively, the microporous matrix can be formed of polyamide,polyester, polysulfone such as polyethersulfone (PES), cellulose orfluoropolymer including polyvinylidene fluoride (PVDF), polyvinylfluoride (PVF) and/or polytetrafluoroethylene (PTFE).

In addition to polymeric composition, the microporous matrix candemonstrate various physical constructions and morphologies. In someembodiments, the microporous matrix is formed of a single layer ofpolymeric material yielding a monolayer construction. Alternatively, themicroporous matrix can comprise multiple layers of polymeric material.Any number of polymeric layers not inconsistent with the objectives ofthe present invention can be used to provide a microporous matrix. Themicroporous matrix, for example, can display a bilayer, trilayer ormultilayer construction. Table I provides various non-limitingconstructions for microporous polymeric matrices of composite membranesdescribed herein.

TABLE I Selected, Non-Limiting Microporous Polymeric MatrixConstructions Monolayer Bilayer Trilayer Multilayer PP PP/PP PP/PP/PPPP/PP/PP/PP PE PE/PE PE/PE/PE PE/PE/PE/PE PP-PE Blend PP/PE PP/PE/PPPP/PP/PP/PE PP-PE copolymer PE/PP PP/PP/PE PP/PP/PE/PE PP-PE Blend/PPPE/PP/PE PP/PE/PE/PE PP-PE Copolymer/PP PE/PE/PP PE/PP/PP/PP PP-PEBlend/PE PP/PP-PE Blend/PP PE/PE/PP/PP PP-PE Copolymer/PE PP/PP-PECopolymer/PP PE/PE/PE/PP PP/PP-PE Blend PP/PP/PP-PE Blend PP/PE/PP/PPPP/PP-PE Copolymer PP/PP/PP-PE Copolymer PP/PP/PE/PP PE/PP-PE BlendPE/PP-PE Blend/PE PP/PE/PE/PP PE/PP-PE Copolymer PE/PP-PE Copolymer/PEPE/PP/PE/PE PE/PE/PP-PE Blend PE/PE/PP/PE PE/PE/PP-PE CopolymerPE/PP/PP/PE PP/PE/PP-PE Blend PP/PP/PP/PP-PE Blend PP/PE/PP-PE CopolymerPP/PP/PP/PP-PE Copolymer PE/PP/PP-PE Blend PP/PP/PP-PE Blend/PPPE/PP/PP-PE Copolymer PP/PP/PP-PE Copolymer/PP PP/PP-PE Blend/PEPP/PP-PE Blend/PP/PP PP/PP-PE Copolymer/PE PP/PP-PE Copolymer/PP/PPPE/PP-PE Blend/PP PP-PE Blend/PP/PP/PP PE/PP-PE Blend/PP PP-PECopolymer/PP/PP/PP PE/PE/PE/PP-PE Blend PE/PE/PE/PP-PE CopolymerPE/PE/PP-PE Blend/PE PE/PE/PP-PE Copolymer/PE PE/PP-PE Blend/PE/PEPE/PP-PE Copolymer/PE/PE PP-PE Blend/PE/PE/PE PP-PE Copolymer/PE/PE/PEPP/PP/PE/PP-PE Blend PP/PP/PE/PP-PE Copolymer PP/PP/PP-PE Blend/PEPP/PP/PP-PE Copolymer/PE PP/PP-PE Blend/PP/PE PP/PP-PE Copolymer/PP/PEPP-PE Blend/PP/PP/PE PP-PE Copolymer/PP/PP/PE PP/PE/PE/PP-PE BlendPP/PE/PE/PP-PE Copolymer PP/PE/PP-PE Blend/PE PP/PE/PP-PE Copolymer/PEPP/PP-PE Blend/PE/PE PP/PP-PE Copolymer/PE/PE PP-PE Blend/PP/PE/PE PP-PECopolymer/PP/PE/PE PE/PE/PP/PP-PE Blend PE/PE/PP/PP-PE CopolymerPE/PE/PP-PE Blend/PP PE/PE/PP-PE Copolymer/PP PE/PP-PE Blend/PE/PPPE/PP-PE Copolymer/PE/PP PP-PE Blend/PE/PE/PP PP-PE Copolymer/PE/PE/PP

Polymeric layers of microporous matrices described herein can alsodemonstrate various morphologies. In some embodiments, morphology of apolymeric layer is induced by the process in which the layer is formed.For example, a polymeric layer can be formed of a dry stretch processwhere pore formation results from stretching a nonporous,semicrystalline extruded polymer composition in the machine direction(MD). FIG. 1 is an SEM image of a microporous polymeric matrix formed ofa monolayer of polypropylene subjected to the dry-stretch process. Asillustrated in FIG. 1, this particular polypropylene matrix demonstratesan interconnected pore structure of elongated or slit-like geometry. Theinterconnected pore structure is continuous with the thicker, fiber-likepolypropylene structures of the matrix.

A polymeric layer can also be formed from a wet process or phaseinversion process where a polymeric composition is mixed with aplasticizer and extruded. Pore formation in the polymeric material isinduced by removal of the plasticizer. The polymeric material may alsobe stretched in MD and/or transverse machine (TD) direction. FIG. 2 isan SEM image of a microporous polymeric matrix formed of a monolayer ofpolyethylene subjected to wet processing. The polyethylene matrix alsodemonstrates an interconnected pore structure continuous with fiber-likepolyethylene structures. In contrast to the image shown in FIG. 1, thepores shown in FIG. 2 have rounder geometries. However, there arepolymer matrix materials formed from dry-stretch processes today (forexamples, processes that involve biaxial stretching of a nonporousprecursor) that also have pores having rounder geometries. In FIG. 2,there is increased overlap of the polyethylene fiber structures, ascompared with FIG. 1, producing a lace-like appearance.

Additionally, a polymeric layer can be formed by a particle stretchprocess whereby a polymeric composition is mixed with particles andextruded. Pores are formed in the polymeric composition duringstretching when interfaces between the polymeric composition andparticles fracture. Formation of porous polymeric layer(s) by particlestretch processes is further detailed in U.S. Pat. Nos. 6,057,061 and6,080,507 which are incorporated herein by reference in theirentireties. FIG. 3 is an SEM image of a microporous polymeric matrixformed of a monolayer of polypropylene subjected to particle stretchprocesses. As illustrated in FIG. 3, the matrix adopts an interconnectedoval pore structure resulting from MD stretching.

Further, polymeric matrices of composite membranes described herein candemonstrate biaxially oriented porous architectures, such as thosedescribed in United States Published Patent Application 2007/0196638 andU.S. patent application Ser. No. 13/044,708 which are each incorporatedherein by reference in their entirety. Also, non-stretched porousmembranes, such as cast membranes, woven or non-woven layers, and thelike, may be used.

As set forth above, a microporous polymeric matrix can be formed ofmultiple polymeric layers. In some embodiments, the polymeric layersdemonstrate similar morphologies as they are each formed by the samedry-stretch process, wet process or particle stretch process.Alternatively, polymeric layers can display mixed morphologies whereinone or more layers are formed by different processes. Embodiments hereincontemplate any combination of polymeric layers formed by dry-stretch,particle stretch and wet processes. For example, individual layers ofthe constructions provided in Table I can demonstrate varyingmorphologies selected from those produced by dry stretch, particlestretch and wet processes. Therefore, polymeric matrices of compositemembranes described herein can display compositional and morphologicalgradients. FIG. 4 is a cross-sectional SEM of a microporous polymericmatrix comprising a multilayer structure illustrating compositional andmorphological gradients according to one embodiment. The microporousmatrix of FIG. 4 has a PP/PE/PP structure, wherein the PE layerdemonstrates a divergent morphology from the sandwiching PP layers.Individual polymeric layers of a microporous matrix described herein canbe coupled by several techniques including lamination, coextrusion orother bonding mechanism.

In addition to the foregoing architectures, a microporous polymericmatrix can also demonstrate various non-woven constructions includingspunbond, spunmelt, meltblown, spunlace, or the like.

In some embodiments, a microporous polymeric matrix has an average poresize ranging from 0.010 μm to 50 μm, in some embodiments, from 0.1 μm to1.0 μm, and in some embodiments, from 0.1 μm to 0.6 μm. Further, amicroporous polymeric matrix can have a thickness according to Table II.

TABLE II Microporous Polymeric Matrix Thickness (μm)  1-100 2-40 4-305-20 6-12Additionally, a microporous matrix can have porosity in excess of 40percent. In some embodiments, a microporous membrane has a porosity of40-95 percent.

As described herein, a microporous polymeric matrix of a compositemembrane has an index of refraction. In some embodiments, a microporouspolymeric matrix can have an index of refraction ranging from about 1.40to about 1.60, and in some embodiments, from about 1.48 to 1.52. Forexample, a microporous membrane formed of polypropylene can display anindex of refraction of 1.49 while a microporous membrane formed ofpolyethylene can display a refractive index of 1.50. When a microporousmatrix is formed of multiple polymeric layers, the polymeric layers canhave the same or substantially similar refractive indices.

In addition to a microporous polymeric matrix, a preferred compositemembrane described herein comprises an electrically conductive coatingdeposited over one or more surfaces of the microporous matrix. Theelectrically conductive coating can coat one or both sides of themicroporous polymeric matrix. Further, the electrically conductivecoating, in some embodiments, penetrates into the pore structure of thematrix, coating surfaces of the pore structure. In coating poresurfaces, the pore structure of the polymeric matrix is maintained andnot occluded by the electrically conductive coating. In someembodiments, the electrically conductive coating is on the molecularscale having a thickness on the order of Angstroms or nanometers.Additionally, the electrically conductive coating can be patterned onone or more surfaces of the microporous polymeric matrix.

The electrically conductive coating can comprise any electricallyconductive material not inconsistent with the objectives of the presentinvention. The electrically conductive coating can be formed of a metalor alloy composition. In one embodiment, the electrically conductivecoating is selected from the group consisting of aluminum, copper,nickel, gold, other noble metals and alloys thereof. Moreover, theelectrically conductive coating can be formed of a light transmissiveconducting oxide including indium tin oxide (ITO), gallium indium tinoxide (GITO), zinc indium tin oxide (ZITO), fluorine doped tin oxide ordoped zinc oxide. Alternatively, the electrically conductive coating canbe provided as an organic material. Electrically conductive organicmaterials such as graphite, graphene, carbon nanoparticles and/orelectrically conductive polymeric species can be used to provide theelectrically conductive layer. Electrically conductive polymeric speciescan include intrinsically conductive polymers, which may be doped, andwhich may include, but are not limited to, poly(thiophenes),poly(paraphenylenes), polydiacetylenes, polyacetylenes,poly(paraphenylenevinylenes), polyaniline and derivatives thereof.

Compositional identity of the electrically conductive layer can beselected according to several considerations including desiredconductivity of the layer and/or desired optical properties of thecomposite membrane. In some embodiments, the electrically conductivelayer provides a sheet resistivity of 1-500 Ω/sq or less, or in someembodiments, 1-20 ohm/sq.

A composite membrane described herein can further comprise fillermaterial in the pore structure of the microporous polymeric matrix, thefiller material preferably having an index of refraction substantiallymatching the index of refraction of the polymeric matrix. In someembodiments, the filler material is added to the pore structure of themicroporous polymeric matrix to provide the composite membrane thedesired optical clarity properties. Addition of the filler material, forexample, can further enhance the optical clarity of the compositemembrane rendering the membrane transparent or substantiallytransparent.

In embodiments wherein the microporous matrix is formed of multiplepolymeric layers, the polymeric layers can be substantially indexmatched, thereby permitting the refractive index of the filler materialto match or substantially match each of the polymeric layers. Forexample, PP and PE layers of a multilayer construction can be indexmatched permitting compatibility of each layer with the refractive indexof the filler material.

Suitable filler material having the requisite refractive index can besolid or semi-solid. In some embodiments, for example, filler materialis an adhesive, in some embodiments, optical adhesive filler material.In addition to imparting desired optical properties, adhesive fillermaterial can facilitate incorporation of composite membranes describedherein into various optoelectronic devices, including touchscreendevices. Filler material can be incorporated into the interconnectedpore structure of the microporous polymeric matrix by severaltechniques. Filler material, in some embodiments, is flowed into thepore structure followed by hardening or increasing the viscosity of thefiller to a substantially non-flowable state.

Composite membranes described herein, in some embodiments, exhibit anoptical transparency of at least about 90 percent or at least about 95percent between 450 nm and 750 nm (wavelengths covering the visiblespectrum of light). Further, composite membranes described herein, insome embodiments, are flexible. Flexibility of the composite membranescan permit their use in flexible optoelectronic devices includingflexible touchscreen devices.

In another aspect, optoelectronic devices are provided incorporatingcomposite membranes described herein. In some embodiments, anoptoelectronic device is a touchscreen device comprising a display and acomposite membrane positioned over the display, the composite membranecomprising a microporous polymeric matrix having an interconnected porestructure and an index of refraction. An electrically conductive coatingis (or multiple coatings are) deposited over one or more surfaces of themicroporous polymeric matrix. The composite membrane can furthercomprise filler material having an index of refraction substantiallymatching the index of refraction of the polymeric matrix. Alternatively,filler material can be chosen to have a refractive index substantiallymatching a glass lens or covering the touch screen device. Thus, in someembodiments, depending on optical preferences, the refractive index ofthe filler material may be chosen to be closer to that of the polymer inthe microporous polymeric matrix, or closer to that of the materialmaking up the glass lens or covering for the touch screen or device orthe like. Matching refractive indices of the filler material and glasscomponent of the touch screen device can enhance anti-reflectiveproperties. A composite membrane positioned over the display can haveany construction and/or properties described herein. Also, there can beone or more composite membrane layers. For example, both capacitive andresistive touch screens use two layers of clear conductive material.

A touchscreen device can refer to any of a number of display and/orcontrol screens that can be operated by touching the display area of thescreen, including with a finger or stylus. For example, a touch screencan include a resistive touch screen, a surface capacitive touch screen,a projected capacitive touch (PCT) touch screen, a surface acousticwaves (SAW) touch screen, an infrared grid touch screen, an opticalimaging touch screen, a dispersive signal technology touch screen or anacoustic pulse recognition touch screen. A capacitive touch screen canbe a mutual capacitance or self-capacitance touch screen. Moreover, atouch screen can be a single-touch or multi-touch screen.

A composite membrane described herein can provide various properties tothe touch screen device. For example, in some implementations, acomposite membrane described herein functions as a protective coatingfor the touch screen device or for a component of the touch screendevice. In other implementations, a composite membrane functions as anelectrically conductive layer or as a conductive coating. In some cases,electrical conduction can occur in the plane of a composite membrane.Further, a composite membrane described herein can be used in a touchscreen architecture as a replacement for a transparent conductivematerial, such as a glass substrate coated with indium tin oxide (ITO).In some implementations described herein, a composite membrane functionsas both a protective coating and a conductive layer or conductivecoating. Using a composite membrane as a protective coating and/or anelectrically conductive layer or coating can provide resistance todamage from external moisture, oils, dirt, or dust to a touch screen.Further, in some embodiments, a composite membrane can provide one ormore of the foregoing advantages while also exhibiting opticaltransparency and/or in-plane electrical conductivity.

In a further aspect, methods of making composite membranes are describedherein. A method of making a composite membrane, in some embodiments,comprises providing a microporous polymeric matrix having aninterconnected pore structure and an index of refraction and depositingan electrically conductive coating over one or more surfaces of themicroporous matrix. Further, filler material can be deposited in thepore structure of the polymeric matrix, the filler material having anindex of refraction substantially matching the index of refraction ofthe polymeric matrix. A composite membrane produced in accordance withmethods described herein can have any construction and/or propertiesdetailed above.

A microporous polymeric matrix having an interconnected pore structurecan be provided according to dry-stretch, particle stretch or wetprocesses described above. Moreover, multiple porous polymeric layersproduced by such processes can be combined to provide a multilayermicroporous polymeric matrix.

Deposition of the electrically conductive coating can be administeredaccording to several processes. In some embodiments, for example, ametal/alloy electrically conductive coating is deposited by one or morephysical vapor deposition (PVD) techniques, such a thermal evaporationor sputtering. Moreover, organic electrically conductive coatings, insome embodiments, are spin cast onto the microporous polymeric matrix.As described herein, the electrically conductive coating can coat one orboth sides of the microporous polymeric matrix. In some embodiments, theelectrically conductive coating is patterned on one or more surfaces ofthe microporous polymeric matrix. Patterning can be administered by oneor more lithographic, masking and/or screening techniques.

Further, the electrically conductive coating, in some embodiments,penetrates into the pore structure of the polymeric matrix, coatingsurfaces of the pore structure. In coating pore surfaces, the porestructure of the polymeric matrix is maintained and not occluded by theelectrically conductive coating. In some embodiments, the electricallyconductive coating is on the molecular scale having a thickness on theorder of Angstroms or nanometers.

As described herein, filler material can be deposited in the porestructure of the polymeric matrix, the filler material having an indexof refraction substantially matching the index of refraction of thepolymeric matrix. In some embodiments, the filler material may have anindex of refraction matching a glass lens or other optical component ofan optoelectronic device.

In some embodiments, filler material is flowed into the pore structureand partially or fully solidified. Filler material can be deposited inthe pore structure of the microporous polymeric matrix prior orsubsequent to deposition of the electrically conductive coating. Whenplaced in the pore structure prior to deposition of the electricallyconductive coating, the filler material can be covered by theelectrically conductive coating. Placement of filler material in thepore structure of the microporous polymeric matrix can preclude theelectrically conductive coating from being deposited on surfaces of thepore structure. Alternatively, the electrically conductive coating canbe deposited on surfaces of the pore structure prior to introduction ofthe filler material.

These and other embodiments are further illustrated by the followingnon-limiting examples.

Example 1

A Celgard 2500 microporous polypropylene matrix (25 μm thickness) ismetalized on one side via a vapor deposition process with aluminum metalto a sheet resistivity of between 0-500 Ω/sq. The metallization can beperformed with patterning (mask, silk screening, etc.) associated withtouch screen addressing technologies. The metalized microporous matrixcan now be used in conjunction with a filler material to obtain acomposite membrane having the desired optical clarity properties. Inthis case, an optical adhesive with a refractive index matching thepolypropylene matrix (i.e. NOA 148 from Norland Products) can be used tosimultaneously fill the matrix and provide adhesive properties to thetouchscreen glass surface, as well as the supporting layers below.

Example 2

A Celgard 2500 microporous polypropylene matrix (25 μm thickness) istreated on one side via a vapor deposition process with ITO to a sheetresistivity of between 0-500 Ω/sq. The sputtering can be performed withpatterning (mask, silk screening, etc.) associated with touch screenaddressing technologies. The metalized microporous matrix can now beused in conjunction with a filler material to obtain the desired opticalclarity properties. In this case, an optical adhesive with a refractiveindex matching the polypropylene matrix (i.e. NOA 148 from NorlandProducts) can be used to simultaneously fill the matrix and provideadhesive properties to the touchscreen glass surface, as well as thesupporting layers below.

Example 3

A Celgard 2500 microporous polypropylene matrix (25 μm thickness) ismetalized on two sides via a vapor deposition process with aluminummetal to a sheet resistivity of between 0-500 Ω/sq. The metallizationcan be performed with patterning (mask, silk screening, etc.) associatedwith touch screen addressing technologies. A two sided patterning can beused for a “one layer” capacitive touch screen construction. Themetalized microporous matrix can now be used in conjunction with afiller material to obtain the desired optical clarity properties. Inthis case, an optical adhesive with a refractive index matching thepolypropylene matrix (i.e. NOA 148 from Norland Products) can be used tosimultaneously fill the matrix and provide adhesive properties to thetouchscreen glass surface, as well as the supporting layers below.

Example 4

A Celgard 2500 microporous polypropylene matrix (25 μm thickness) istreated on two sides via a vapor deposition process with ITO to a sheetresistivity of between 0-500 Ω/sq. The sputtering can be performed withpatterning (mask, silk screening, etc.) associated with touch screenaddressing technologies. A two sided patterning can be used for a “onelayer” capacitive touch screen construction. The metalized microporousmatrix can now be used in conjunction with a filler material to obtainthe desired optical clarity properties. In this case, an opticaladhesive with a refractive index matching the polypropylene matrix (i.e.NOA 148 from Norland Products) can be used to simultaneously fill thematrix and provide adhesive properties to the touchscreen glass surface,as well as the supporting layers below.

Example 5

A Celgard EZ1590 microporous polypropylene matrix (15 μm thickness) ismetalized on one side via a vapor deposition process with aluminum metalto a sheet resistivity of between 0-500 Ω/sq. The metallization can beperformed with patterning (mask, silk screening, etc.) associated withtouch screen addressing technologies. The metalized microporous matrixcan now be used in conjunction with a filler material to obtain thedesired optical clarity properties. In this case, an optical adhesivewith a refractive index matching the polypropylene matrix (i.e. NOA 148from Norland Products) can be used to simultaneously fill the matrix andprovide adhesive properties to the touchscreen glass surface, as well asthe supporting layers below.

Example 6

A Celgard EZ1590 microporous polypropylene matrix (15 μm thickness) istreated on one side via a vapor deposition process with ITO to a sheetresistivity of between 0-500 n/sq. The sputtering can be performed withpatterning (mask, silk screening, etc.) associated with touch screenaddressing technologies. The metalized microporous matrix can now beused in conjunction with a filler material to obtain the desired opticalclarity properties. In this case, an optical adhesive with a refractiveindex matching the polypropylene matrix (i.e. NOA 148 from NorlandProducts) can be used to simultaneously fill the matrix and provideadhesive properties to the touchscreen glass surface, as well as thesupporting layers below.

Example 7

A Celgard EZ1590 microporous polypropylene matrix (15 μm thickness) ismetalized on two sides via a vapor deposition process with aluminummetal to a sheet resistivity of between 0-500 Ω/sq. The metallizationcan be performed with patterning (mask, silk screening, etc.) associatedwith touch screen addressing technologies. A two sided patterning can beused for a “one layer” capacitive touch screen construction. Themetalized microporous matrix can now be used in conjunction with afiller material to obtain the desired optical clarity properties. Inthis case, an optical adhesive with a refractive index matching thepolypropylene matrix (i.e. NOA 148 from Norland Products) can be used tosimultaneously fill the matrix and provide adhesive properties to thetouchscreen glass surface, as well as the supporting layers below.

Example 8

A Celgard EZ1590 microporous polypropylene matrix (15 μm thickness) istreated on two sides via a vapor deposition process with ITO to a sheetresistivity of between 0-500 Ω/sq. The sputtering can be performed withpatterning (mask, silk screening, etc.) associated with touch screenaddressing technologies. A two sided patterning can be used for a “onelayer” capacitive touch screen construction. The metalized microporousmatrix can now be used in conjunction with a filler material to obtainthe desired optical clarity properties. In this case, an opticaladhesive with a refractive index matching the polypropylene matrix (i.e.NOA 148 from Norland Products) can be used to simultaneously fill thematrix and provide adhesive properties to the touchscreen glass surface,as well as the supporting layers below.

Example 9

A Celgard K2045 microporous polyethylene matrix (20 μm thickness) ismetalized on one side via a vapor deposition process with aluminum metalto a sheet resistivity of between 0-500 Ω/sq. The metallization can beperformed with patterning (mask, silk screening, etc.) associated withtouch screen addressing technologies. The pattern can be done on one ormore surfaces of the polymeric matrix, including the surfaces of thepores. The metalized microporous matrix can now be used in conjunctionwith a filler material to obtain the desired optical clarity properties.In this case, an optical adhesive with a refractive index matching thepolypropylene matrix (i.e. NOA 148 from Norland Products) can be used tosimultaneously fill the matrix and provide adhesive properties to thetouchscreen glass surface, as well as the supporting layers below.

Example 10

A Celgard K2045 microporous polyethylene membrane (20 μm thickness) istreated on one side via a vapor deposition process with ITO to a sheetresistivity of between 0-500 Ω/sq. The sputtering can be performed withpatterning (mask, silk screening, etc.) associated with touch screenaddressing technologies. The metalized microporous matrix can now beused in conjunction with a filler material to obtain the desired opticalclarity properties. In this case, an optical adhesive with a refractiveindex matching the polypropylene matrix (i.e. NOA 148 from NorlandProducts) can be used to simultaneously fill the matrix and provideadhesive properties to the touchscreen glass surface, as well as thesupporting layers below.

Example 11

A Celgard K2045 microporous polyethylene membrane (20 μm thickness) ismetalized on two sides via a vapor deposition process with aluminummetal to a sheet resistivity of between 0-500 Ω/sq. The metallizationcan be performed with patterning (mask, silk screening, etc.) associatedwith touch screen addressing technologies. A two sided patterning can beused for a “one layer” capacitive touch screen construction. Themetalized microporous matrix can now be used in conjunction with afiller material to obtain the desired optical clarity properties. Inthis case, an optical adhesive with a refractive index matching thepolypropylene matrix (i.e. NOA 148 from Norland Products) can be used tosimultaneously fill the matrix and provide adhesive properties to thetouchscreen glass surface, as well as the supporting layers below.

Example 12

A Celgard K2045 microporous polyethylene membrane (20 μm thickness) istreated on two sides via a vapor deposition process with ITO to a sheetresistivity of between 0-500 Ω/sq. The sputtering can be performed withpatterning (mask, silk screening, etc.) associated with touch screenaddressing technologies. A two sided patterning can be used for a “onelayer” capacitive touch screen construction. The metalized microporousmatrix can now be used in conjunction with a filler material to obtainthe desired optical clarity properties. In this case, an opticaladhesive with a refractive index matching the polypropylene matrix (i.e.NOA 148 from Norland Products) can be used to simultaneously fill thematrix and provide adhesive properties to the touchscreen glass surface,as well as the supporting layers below.

Example 13

Any of the foregoing porous polymeric matrices can be conductivelycoated on one or both sides by the processes of thermal metallization,sputtering, chemical grafting, electroless plating, polymerization, etc.

Materials that can be used for conductivity are metals such as gold,silver, aluminum, nickel, copper, platinum, palladium, iron, etc.Furthermore, alloys of these and others may be used. ITO is particularlyuseful, as are other variants thereof (various doped zinc oxides or tinoxides). Inherently conductive polymers can also be patterned on thesurface in a similar manner. Poly(thiophenes), poly(paraphenylenes),polydiacetylenes, polyacetylenes, poly(paraphenylenevinylenes), etc. areclasses of conductive polymers that could be chemically grafted to thesurface or patterned with a vapor deposition method or solution printingmethod to provide the requisite conductivities. Other materials such ascarbon nanotubes, carbon fullerenes, and graphene may be conductivematerials that could be used in the future.

Example 14

A microporous polymeric matrix that has been metalized or patterned withan electrically conductive surface on one or both sides can be includedin a continuous process of manufacturing touch screens. A roll ofmetalized matrix can be patterned and shipped to a touch screenmanufacturer. Said manufacturer can take the prepatterned roll and applythe film to a glass lens. This can be done directly from the roll andaligned very easily as the conductive substrate is opaque beforefilling/adhering.

After the alignment has occurred on the glass lens, application of arefractive index matching optical adhesive (matching either therefractive index of the porous matrix, or the selected glass lens) isapplied to the back side of the film. Since the film is highly porous,the adhesive can be applied to only one side, allowed to seep through orforced through by a mechanical inducement, and can provide adhesionthrough the porous material simultaneously on two sides. In this manner,one adhesive step can be removed from the process.

In accordance with at least selected embodiments, aspects or objects,the present invention relates to polymeric membranes, to electricallyconductive membranes, to electrically conductive transparent membranes,new or improved substrates for such membranes, methods of production ofsuch membranes, and/or methods of use of such membranes or substrates.

In one aspect, microporous membranes are described herein demonstratingcomposite architectures and properties suitable for electronic and/oroptical applications. In some embodiments, a composite membranedescribed herein includes a microporous polymeric matrix or substratehaving an interconnected pore structure and an index of refraction andan electrically conductive coating deposited over one or more surfacesof the microporous polymeric matrix. In other embodiments, the pores arefilled and the membranes are substantially transparent.

In accordance with at least certain embodiments, aspects or objects, thepresent invention relates to conductive, transparent, translucent,and/or reflective polymeric membranes or materials, substrates for suchmembranes or materials, methods of production of such substrates,membranes or materials, and/or methods of use of such substrates,membranes or materials. In accordance with at least certain selectedembodiments, the present invention relates to electrically conductivemembranes or materials, preferably electrically conductive transparentmembranes or materials, new or improved porous or microporous substratesfor such membranes, methods of production of such conductive membranesor materials, and/or methods of use of such membranes, materials orsubstrates.

The membrane and/or material may be conductive and/or reflective, forexample, depending on the material deposited, the manner of deposition,if the pores remain open or unfilled, and/or the like. For example, inFIGS. 5 and 6, the metalized side was metalized, coated, treated ordeposited with aluminum deposition on the surface of the porous film,matrix or substrate, and provides both conductivity and reflectivity(see the dull, mirror-like surface of the right side of FIG. 6, by wayof example, where the pores of the membrane are not filled). If thealuminum were deposited in a pattern (such as parallel lines), therewould be conductivity but perhaps no reflectivity. Also, certainnon-conductive coating materials may provide reflectivity withoutconductivity. Also, the level of reflectivity and/or opaqueness versusthe level of transparency and/or translucence can be modified oradjusted by filling pores with certain amounts of material having acertain refractive index.

FIG. 5 is a photographic image showing side by side comparison of thewhite uncoated (non-metalized) surface or side and the metallic, shinyor reflective side of a metalized or coated membrane or material(Celgard® EZ2090) having a microporous polymeric matrix according to aparticular embodiment of the present invention. Although FIG. 5 showsonly one side metalized, it is understood that one or both sides may bemetalized and that the pores may be filled or unfilled. FIGS. 5, 7, 8and 9 show unfilled pores. FIG. 6 shows a portion having filled pores.In accordance with the particular example of FIG. 6, the pores werefilled with a hand sanitizer mixture having about 62% ethanol. One couldalso fill the pores of the membrane with oil, IPA, solvent, polymer, apolymer and solvent mixture, and/or the like, to make it clear ortransparent. The preferred filler is one that works in the particularapplication and that makes the membrane clear or nearly clear when thepores of the membrane are filled with the filler material.

FIG. 6 is a photographic image of the metalized membrane or material ofFIG. 5 (Celgard® EZ2090) placed over a display screen of a consumerelectronic device, in particular, a BlackBerry device, with the filledportion of the metalized membrane or material being transparent ortranslucent and the unfilled portion being opaque and reflective.

FIG. 7 is a surface SEM of the metalized surface of the metalizedmembrane or material of FIG. 5 (Celgard® EZ2090) at 1,000×magnification.

FIG. 8 is a surface SEM of the metalized surface of the metalizedmembrane or material of FIG. 5 at 5,000× magnification.

FIG. 9 is a surface SEM of the metalized surface of the metalizedmembrane or material of FIG. 5 at 20,000× magnification. The aluminumflakes are barely visible on the fibrils.

In accordance with at least selected embodiments, objects, or aspects,the present invention may address the need for or provide microporousmembranes suitable for electrically conductive applications and/orapplications involving high temperature, oxidative, and/or othercorrosive environments, and/or relates to conductive, transparent,translucent, partially reflective, and/or reflective polymeric membranesor materials, substrates for such membranes or materials, methods ofproduction of such substrates, membranes and/or materials, and/ormethods of use of such substrates, membranes and/or materials. Inaccordance with at least selected embodiments, the present inventionrelates to electrically conductive membranes or materials, preferablyelectrically conductive transparent or semi-transparent membranes ormaterials, new or improved porous or microporous substrates for suchmembranes, methods of production of such conductive membranes ormaterials, and/or methods of use of such membranes, materials orsubstrates.

Various embodiments of the invention have been described in fulfillmentof the various objects of the invention. It should be recognized thatthese embodiments are merely illustrative of the principles of thepresent invention. Numerous modifications and adaptations thereof willbe readily apparent to those skilled in the art without departing fromthe spirit and scope of the invention.

That which is claimed is:
 1. A transparent or translucent membranecomprising: a microporous polymeric matrix having an interconnected porestructure and an index of refraction; and a filler material fills thepore structure of the polymeric matrix, the filler material having anindex of refraction substantially matching the index of refraction ofthe polymeric matrix, wherein substantially matching means the fillermaterial has an index of refraction that is +/−0.1 relative to the indexof refraction of the polymeric matrix.
 2. The membrane of claim 1wherein the filler material is one of a solid or an adhesive.
 3. Themembrane of claim 1 wherein the membrane is transparent.
 4. The membraneof claim 1 wherein the membrane is translucent.
 5. The membrane of claim1 wherein the microporous polymeric matrix is formed of one or morepolyolefins, polyamides, polyesters, polysulfones, celluloses,fluoropolymers, and combinations or blends thereof.
 6. The membrane ofclaim 1 wherein the microporous polymeric matrix is formed of one ormore polyolefins selected from the group consisting of polyethylene,polypropylene, and combinations, copolymers and blends thereof.
 7. Themembrane of claim 1 wherein the polymeric matrix is formed of a singlelayer of polymeric material.
 8. The membrane of claim 1 wherein thepolymeric matrix comprises multiple layers of polymeric material.
 9. Themembrane of claim 8 wherein individual layers of the polymeric matrixare selected from the group consisting of polyethylene, polypropylene,and combinations, copolymers and blends thereof.
 10. The membrane ofclaim 1 having a thickness of 1 μm to 100 μm and the thickness includingan optional metalized, conductive or reflective coating or depositionover one or more surfaces of the microporous polymeric matrix.
 11. Themembrane of claim 1 having a thickness of 5 μm to 20 μm.
 12. Ametalized, conductive or reflective composite membrane comprising: amicroporous polymeric matrix having an interconnected pore structure:and a metalized, conductive or reflective coating or deposition over oneor more surfaces of the microporous polymeric matrix.
 13. The compositemembrane of claim 12 further comprising filler material in the porestructure of the polymeric matrix, the filler material having an indexof refraction substantially matching an index of refraction of thepolymeric matrix.
 14. The composite membrane of claim 13 wherein thefiller material is one of a solid or an adhesive.
 15. The compositemembrane of claim 12 wherein the membrane is transparent or translucent.16. The composite membrane of claim 12 wherein the microporous polymericmatrix is formed of one or more polyolefins, polyamides, polyesters,polysulfones, celluloses, fluoropolymers, and combinations, mixtures orblends thereof.
 17. The composite membrane of claim 16 wherein the oneor more polyolefins are selected from the group consisting ofpolyethylene, polypropylene, and copolymers, mixtures, and blendsthereof.
 18. The composite membrane of claim 12 wherein the polymericmatrix is formed of a single layer of polymeric material.
 19. Thecomposite membrane of claim 12 wherein the polymeric matrix comprisesmultiple layers of polymeric material.
 20. The composite membrane ofclaim 19 wherein individual layers of the polymeric matrix are selectedfrom the group consisting of polyethylene, polypropylene, andcopolymers, mixtures, and blends thereof.
 21. The composite membrane ofclaim 12 having a thickness of 1 μm to 100 μm and the composite membraneoptionally adapted to serve as a battery separator.
 22. The compositemembrane of claim 12 having a thickness of 5 μm to 20 μm.
 23. Thecomposite membrane of claim 12 wherein the conductive coating ordeposition comprises an electrically conductive coating or deposition ofat least one metal or alloy.
 24. The composite membrane of claim 12wherein the membrane is flexible.
 25. The composite membrane of claim 12having sheet resistance of 1-500 Ω/sq.
 26. A touchscreen devicecomprising: a display; and the composite membrane of claim
 12. 27. Amethod of making the composite membrane of claim 12 comprising the stepsof: providing a microporous polymeric matrix having an interconnectedpore structure and an index of refraction; and adding a metalized,conductive or reflective coating or deposition over one or more surfacesof the microporous polymeric matrix.
 28. The method of claim 27 whereinin the adding step an electrically conductive coating or deposition ispatterned over one or more surfaces of the microporous polymeric matrix.